Device on electric power hand tools

ABSTRACT

For the attachment of a battery pack to a power hand tool, a plug-type connection is suggested which has a circular insertion part on the battery casing and a corresponding locating arrangement (3) on the power hand tool. Both parts have concentric power contacts and locking means, which when the casing (16) is axially inserted, engage automatically. By a short twist, the locking means can be released, and the battery casing (16) can be removed for recharging.

BACKGROUND OF THE INVENTION

The present invention relates to a device on electric hand power toolsfor a mechanical and electrical coupling of batteries.

More particularly, it relates to a device of the above mentioned generaltype, which has a locating arrangement for coupling of batteries.

From DE-A-37 42 268, an electric tool with a facility for locating andretaining battery packs in and/or on the tool casing is known, in whichthe battery pack can be fixed to the hand tool by means of an additionalring. The electric tool, the battery pack, and the ring, are fitted withlocking elements, and a pushing and turning movement are required forthe coupling of the battery pack. Before locating the battery pack, theuser must further make sure that the ring is in the correct rotationalposition relative to the electric tool. The manufacture and theoperation of this coupling facility are relatively elaborate. Moreover,the battery contacts are open to the outside of the battery pack, whichcan lead to short circuiting.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide adevice for mechanical and electrical coupling of batteries on electricpower hand tools, which avoids the disadvantaged of the prior art.

In keeping with these objects and with others which will become apparentherinafter, one feature of the present invention resides, brieflystated, in a device for mechanical and electrical coupling of batteriesin accordance with which within the locating arrangement a double bushis arranged with concentrically located electrical power contacts towhich corresponding electrical power contacts on a battery casing areassigned, and locking means are arranged for detachable mounting of thebattery casing, and the battery casing can be rotated in the locatingarrangement.

In accordance with another feature of the present invention a casing formechanical and electrical coupling of batteries to electrical power handtools is provided, which has a concentrically circular insertion partand, in accordance in addition, within the insertion part a double plugis provided with concentrically arranged electrical power contacts whichare connected to the batteries and locking means is provided forattachment of the casing to the power hand tool.

When the device and the housing are designed in accordance with thepresent invention, they have the advantage that the connection of thebatteries is simplified and that the electrical contacts are protectedfrom bodily contact and shortcircuit. The subject of the invention doesnot require any operating element on the power hand tool, but requires,in addition to holding the unit, only one hand for connection andrelease of the battery casing. To prevent accidental release, an axialmovement may be provided for, to take place before the turning movement.

In accordance with further advantageous developments and improvements itis of particular advantage that locking means which are designed asundercut recesses are provided in the locating arrangement of the powerhand tool which are of angular design in the direction towards thepush-in side, and in at least one circumferential direction, they areradiused or chamfered. This facilitates simple snap-in of the lockingmeans on axial insertion of the battery casing into the locatingarrangement, and a simple release of the locking means by twisting the.battery casing against the locating arrangement. Coaxial grooves whichare asymmetrically distributed at the circumference of the locatingarrangement have the advantage that the battery casing can be insertedonly in a defined twisting position, so that additionally arrangedsimple contact surfaces come into contact with their mating surface in amanner which is positionally correct for a signal transmission. Thismoreover ensures the correct twisting position appropriate for the tool,of the usually not circular battery casing. It is also of particularadvantage to design the locking means, either on the locatingarrangement or on the inserting part, as elastic detents which engage inan undercut at the respective mating part of the facility. Thedistribution of the locking means, corresponding to the distribution ofgrooves on the locating arrangement, ensures the correct twistingposition of the battery casing vis-a-vis the power hand tool in a simplemanner and without an additional device on the inserting part. Thearrangement of the electrical power contacts within the couplingelements protects these from being accidentally contacted, which couldresult in corrosion or in short-circuiting. This is particularlyimportant for the battery casing which users will occasionally andunthinkingly place in tool boxes.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention, itself, however, both as to its construction and its methodof operation, together with additional objects and advantages thereof,will be best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section through a .locating arrangement of a powerhand tool.

FIG. 2 shows a top view of this locating arrangement, FIG. 3 shows abattery casing with the inserting part, and FIG. 4 shows a top view ofthe inserting part.

DESCRIPTION OF THE PREFERRED EMBODIMENT

On a housing 2 of a power hand tool shown in part only FIGS. 1 and 2, alocating arrangement 3 which extends in a cupular shape into thehousings 2 is arranged with a front face 4 facing outwards, which has anessentially circular cross-section. Concentrically situated within thelocating arrangement 3 is an inner bush 5 and an outer sleeve 6, both ofwhich are set back in relation to the front face 4. The bush 5 and thesleeve 6 form a double bush 7 with electrical power contacts 8 and 9.For this purpose, the bush 5 and sleeve 6 can be designed either asmetal sleeves, or, they may be faced with metal on their inner side. Thepower contacts 8, 9 are electrically connected to a drive motor of thepower hand tool which is not Shown.

The locating arrangement 3 has three coaxial grooves 11 asymmetricallydistributed around its circumference. Towards the front face 4, thegrooves 11 are expanded by guide-in chamfers 12. Undercut recesses 13,which are of angular design towards the front face 4, i.e. the insertionside, and radiused on both sides in the circumferential direction, arearranged on that inner end of the grooves 11 which faces away from thefront face 4. On a base area 14 of the locating arrangement, twomushroom shaped contact areas 15 are asymmetrically arranged for signaltransmission.

The casing 16, shown partially in FIGS. 3 and 4, in which preferablyrechargeable batteries 17 will be accommodated, has an essentiallycircular insertion part 18 for connection with the power hand tool.Three locking means 19, designed as elastic detents, projectasymmetrically, corresponding to the grooves 11, from the circularcircumference. Each of the detents 19 has a projection 20, which whenpushed into the locating arrangement 3 engages in the undercuts formedby the recesses 13. A cavity 21 is formed behind the detents 19,allowing the detents 19 to spring back towards the centre of theinsertion part 18. A concentric double plug 23 with an inner plug pin 24and a plug sleeve 25 arranged with a spacing around it, is centrallyarranged in the inserting part 18. The two plug parts 24, 25 each haveon their outer circumference an annular, springy, power contact 26, 27which is connected to the batteries 17. The-power contacts 26, 27 areaccommodated concealed within the double plug 23 or the plug part 18, sothat they cannot be touched by hand; for this purpose, they terminateeven before the point of the plug pin 24 and the plug sleeve 25, and areaxially overlapped in this area. Between the double plug 23 and theouter circumference of the plug part 18, there are contact faces 28which may be of spring-loaded design, arranged opposite the contactfaces 15. These contact faces are used for signal transmission, forexample, for temperature monitoring of the rechargeable batteries 17.

The handling of the inserting device is extremely simple. The batterycasing 16 is held in one hand and, according to the position of thedetents 19 and the grooves 11, is simply inserted into the locatingarrangement 3 in an axial direction. The detents 19 are pressed inwardsalong the guide-in chamfers 12 and subsequently engage automatically inthe recesses 13. The insertion simultaneously effects theinterconnection of the power contacts 8, 9 and 26, 27. The contact faces15 and 29 will also, if required, come into conductive contact with eachother. The casing 16 is thus, mechanically and electrically securelyconnected to the housing 2 of the power hand tool. To release thebattery casing 16, it Should be twisted by approximately 30 degrees tothe right or left. In this operation, the detents 19 slide with theirradiused edges along the radiused edges of the recesses 13 and aredeflected inwards during this action, until they have fully emerged fromthe recesses 13. The concentric arrangement of the power contacts doesnot obstruct the rotation of the battery casing 16. With the detents 19disengaged, the battery casing 16 can be easily released from the powerhand toll by axially withdrawing it.

In order to prevent accidental release of the battery casing 16, thetwisting movements the casing in normal position can alternatively beprevented by appropriate means, such as providing in this region sharpedges to the recesses 13 and/or sharp side edges on the detents 13. Todisengage the snap-in locking connection initially requires an axialpressure in the direction towards the locating arrangement 3, so thatthe detents 19 enter into the region of radiused edges--not shown--ofthe recess 13. In this position, disengagement of the snap-in connectionas shown in the embodiment example is again possible, with the sharpedges of the detents 19 in appropriate circumstances sliding over theradiused edges of the recess 13.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in adevice for mechanical and electrical coupling of batteries on electricpower hand tools and a casing for mechanically and electrically couplingto electric power hand tools, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthan, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.
 1. A device for mechanical andelectrical coupling of batteries to electric power hand tools,comprising a locating arrangement having a substantially circularcross-section; a double bush located in said location arrangement andprovided with concentrically arranged electrical power contactsconnectable with electrical power contacts of batteries; and lockingmeans provided in said locating arrangement for detachably mounting abattery casing so that the battery casing can be rotated in saidlocating arrangement.
 2. A device as defined in claim 1, wherein saidlocking means is formed so that the battery casing can be connected tosaid locating arrangement by an axial insertion during which saidlocking means automatically lock the battery casing in said locatingarrangement.
 3. A device as defined in claim 2, wherein said lockingmeans include recesses.
 4. A device as defined in claim 4, wherein saidrecesses are angular at an insertion side and radiused in at least onecircumferential direction.
 5. A device as defined in claim 1, whereinsaid locating arrangement has coaxial grooves asymmetrically distributedaround its circumference and having guide-in chamfers in a front regionas considered in direction of insertion of the battery casing into saidlocating arrangement.
 6. A device as defined in claim 1, wherein saidlocating arrangement has non-concentrically arranged contact faces fortransmitting electrical signals.
 7. A casing for batteries to providemechanical and electrical coupling of the batteries to electrical powerhand tools having a bush, the casing comprising a substantially circularinsertion part, a double plug provided in said insertion part and havingconcentrically arranged electrical power contacts which are connectableto the batteries; and locking means provided in said insertion part forattaching said insertion part to a power hand tool.
 8. A casing asdefined in claim 7, wherein said locking means include elastic detentswhich engageable in an undercut recess on a locating arrangement of thepower hand tool.
 9. A casing as defined in claim 7, wherein said lockingmeans project beyond a circumference of said insertion part and areinsertable into grooves of the locating arrangement.
 10. A casing asdefined in claim 7, wherein said power contacts are arranged concealedwithin said insertion part.
 11. A casing as defined in claim 7, whereinsaid insertion part has non-concentrically arranged contact faces fortransmitting electrical signals.